Space station's hull to heave with spare parts

 作者:东梓都     |      日期:2019-02-27 10:16:02
By Kelly Young (Image: NASA) The outside of the International Space Station may soon look like dad’s cluttered garage, with spare parts strewn everywhere. With the number of space shuttle flights limited to no more than 15 before the vehicles retire in 2010, NASA is facing the problem of getting broken gear on the ISS back to Earth for repair. So the agency is trying a new tactic – they are stashing as many spare parts as they can on the ISS now. “The idea is when the shuttle is done [flying], all the unique shuttle items that we have on the ground will be pre-positioned outside [the] space station on spare pallets,” says Bill Gerstenmaier, NASA’s associate administrator of space operations. “So then we’ll essentially have the spares closet full, and we’ll be ready to go ahead and ride out the period of time until the space station ends.” The way science is done on the station may also change. Previously, scientists have had to get any experiments done on the ISS back to Earth for analysis. Now, with limited space on returning shuttles, astronauts onboard the station may be charged with doing some of that analysis on their own. Sometime in the future, the ISS is expected to get a microscope, which would help their work. Currently, the crew is limited to three people, and the astronauts spend most of their time keeping the station running smoothly. But the station is being expanded and could accommodate a crew of six as early as January 2009. This could potentially provide more time for science experiments and analysis. Another way NASA is trying to keep from repairing parts on the ground and sending them back up to space is by adopting a more “disposable philosophy”, Gerstenmaier says. The agency plans to toss unneeded gear overboard after it has extended its useful life (see Astronauts to pitch unwanted gear off space station). One example of this philosophy may manifest itself in the four 270-kilogram control moment gyroscopes that keep the station pointed in the right direction. The spinning gyros have frequently broken down. NASA replaced one of the four current gyros during a 2005 shuttle mission (see Spacewalk installs new gyroscope on station). When gyros need to be replaced in the future, NASA may send up a redesigned version in which each gyro is divided into three or four smaller wheels. This could make it easier to stow these parts on the smaller Russian Progress ships or even the rockets being developed by Space-X and Rocketplane Kistler to reach the station (see NASA awards seed money to two rocket companies). Gerstenmaier says the disposable philosophy may actually prove useful in preparing for longer sojourns on the Moon, where cargo ships probably will not be able to ship broken parts and their replacements to and from Earth. In addition to the problem of getting stuff down to Earth, NASA also has far more equipment on the ground waiting to be taken to the station than they have room to carry on the remaining space shuttles. Between 2007 and 2009, there are 13 metric tonnes of gear that currently has no assigned way of getting to the station. From 2010 through 2015, after the shuttles retire, that figure rises to 62.4 metric tonnes. For the near term, NASA is trying to purchase space for their equipment aboard Russian Progress cargo ships. In December 2006, NASA also asked private companies whether they would have the capability to ship 2 metric tonnes of equipment to the ISS in 2009. The agency cannot yet discuss possible prices or schedules for those flights, however, says agency spokesman John Yembrick. And even after the shuttles retire in 2010, the station will still have several ways of receiving supplies. Three Russian Progress flights and two to three commercial US cargo flights are expected to be made per year. The European Space Agency’s Automated Transfer Vehicle (ATV), which is expected to make its first flight in mid-2007,